Mechanical apparatuses can be joined to a round shaft for the purpose of transmitting torque from the shaft to the apparatus, or vice versa, a means must exist to connect the apparatus to the shaft for this purpose. Prior art apparatuses have used a variety of means for joining to a shaft, including set screws which impinge directly on the shaft through the apparatus. This method is crude and frequently results in slippage and scoring of the shaft if excessive torque is input, or the screws are not tightened properly due to the small surface area contact of the screws on the shaft. Improved methods have been proposed and utilized, such as split hubs, or bushings which can be inserted into an apparatus, and then compressed with a set screw(s). Clamping methods associated with these prior art types utilize a common concept of applying force on the outside of a bushing which has a cylindrical bore. Since in practice the shaft and bore of the apparatus and bushing are not exactly equal in size or shape, it is normal that contact exists between a cylindrical shaft and a clamping bushing or apparatus with a cylindrical bore, only in limited areas. Even in designs where clamping is applied upon opposite sides of a bushing or apparatus with a cylindrical bore, it is possible that only two lines of contact extending axially along the two areas of contact that exist between the shaft and the apparatus as the apparatus is forced to collapse onto the shaft.